Noise suppression device for turbo-jet engines



Dec. 22, 1964 J. A. HAY 3,162,265

NOISE SUPPRESSION DEVICE FOR TURBO-JET ENGINES Filed June 14, 1961 2 Sheets-Sheet 1 INVENTOR mm M'mouy My M03 es, None 000 Nam? mron Icy:

Dec. 22, 1964 J. A. HAY 3,162,265

NOISE SUPPRESSION DEVICE FOR TURBO-JET ENGINES Filed June 14, 1961 2 Sheets-Sheet 2 121 12 20 12g 3. 19 22 a) f T I I R20 122 125 12.9 124 17 127 132 1.24 136 495 179 I I AWAV w I v I l M920 122 125 129 124- I 127 19 I 22 y 1 {9 21 192 I 133 134 135 1% A- l J v 27 15 12 121,20 122 129 14 17 [29. 6. .INvENTbR Jenn ANTHONY My BY nun ATTORNEy- United States Patent 3,162,265 NOISE SUPPRESSIQN DEVIQE FQlR TURlBG -JET ENGINES John A Hay, Addlestone, England, assignor to Vicliers- Armstrongs (Aircraft) Limited, London, England, a British company Filedlune 14,1961, Ser. No. 117,013 Claims priority, application Great Britain, May 5, 1961,

16,424/61 Claims. (Cl. 181-51) With the object of reducing the volume of noise generated by the efflux of a turbo-jet engine of an aeroplane,'the present invention proposes to provide means for decreasing the effective jet velocity, by entraining with the jet efilux additional air. For this purpose there are mounted in the efilux at positions closeto the jet nozzle a plurality of vanes the effect of which will be to induce the admixture of additional air with the jet gases, whereby the effective velocity of the jet is diminished and the volume of noise emanating therefrom is reduced to a tolerable level.

The said vanes, which are conveniently disposed in spaced relationship equiangularly about the axis of the jet efilux, may be mounted upon carriers supported upon the engine nacelle or an adjacent fixed part of the aircraft structure. Mechanism may be provided for moving said carriers so that the assembly of vanes may be extended into or retracted from their operative position during flight when noise reduction is' not required.

The shape of the vanes is arbitrary. The may be rectangular or triangular, with possible intermediate shapes having curved or straight marginal edges. In the case of a triangular shape, the greater span is near the downstream edge, and the span decreases towards a pointed or slightly rounded apex.

It is desirable that the vanes be mounted so that their planes are inclined at an angle of between 3 and 30 to the axis of the jet efliux.

The manner in which this invention may be carried into effect is hereinafter described in greater detail with reference to the accompanying diagrammatic drawings. In said drawings FIG. 1 is a centrally taken longitudinal section of the after part of a turbo-jet engine having noise suppressing apparatus constructed and operating in accordance with the invention, and FIG. 2 is a rear elevation thereof. FIGS. 3, 4, 5 and 6 are diagrams respectively illustrating the portions of the several parts of the apparatus (a) when the vanes are retracted, (b) at an intermediate stage in the operation of extending the vanes, (0) when the vanes occupy their operative position, and (d) at an intermediate stage in the operation of extracting the vanes.

In the drawings, the reference numeral 10 designates the after end of the engine efiiux jet-tube and 11, 11, 11,

i 11, are four housings mounted on the exterior of the tube 10 at equiangularly spaced positions thereon, as shown in FIG. 2. Each such housing 11 contains two fluid-pressure jacks 12 and 13 disposed in side-by-side parallel relationship, said jacks being mounted on a common support 14 which is pivoted to the fixed structure member 15 at 16.

Each jack 12 contains a ram 121 the rod 122 of which is pivotally attached at its outer extremity to a carrier 123 which is arranged to slide longitudinally upon two spaced stops 124, 125 which cooperate with a slot 126, the stop 124 serving to determine the retracted position of the carrier and the stop 125 serving to determine the extended position thereof. At its outer extremity each carrier 123 there is pivotally mounted at 127 a vane 17 which is of triangular shape having an apex 172 extending upstream and a base or greater span at the downstream end. The apex 172 is pointed or slightly rounded. I

Each jack 13 contains a ram 131 the rod 132 of which extends through fixed guide bracket 133. Aft of the bracket 133 the rod 132 is connected pivotally at 134 to a link 135 the opposite end of which is pivoted at 136 to an arm 173 fixed'to the vane 17. I

To extend the vanes 17 from the retracted position shown in FIG. 3, in which condition the whole of the mechanism hereinbefore referred to is" contained within the housings 11, fluid-pressure in the pipe-lines 18, 19 is applied to boith jacks 12 and 13, with the result that the rams forced outwardly, and the vane 17 is extended to the position shown in FIG. 4. Since the pressure in the line 19 exceeds that in the line 18, the vanes are prevented from being deflected before they have cleared the ends of the housings 11. During this stage the ports 20, 21 are open to exhaust. The vanes 17 still occupy positions in which they are respectively substantially parallel to their carriers 123, and to achieve their further movement into the inclined operative positions shown in FIGS. 1, 2 and 5, pressure in the pipe-line 19 is relaxed by opening a relief valve 22, and pressure is applied to the jack 13 through the port 21, the jack 12 being held in the extended condition. To restore the vanes to the housing position, the port 18 is opened to exhaust, the valve 22 remains open, and pressure is applied to both jacks through the ports 20 and 21. The vanes first resume their inoperative position, as shown in FIG. 6, whereafter the whole assembly is retracted to the position shown in FIG. 3.

The mounting of the vanes is preferably such that in the operative position they are inclined at an angle between and 30 to the axis of the jet effiux, indicated by the line X-Y in FIG. 1.

The effect of extending the vanes 17 to the position shown in FIGS. 1, 2 and 5 is to cause additional air to be entrained with the jet efilux gases. The effective jet velocity is thereby diminished, in consequence of which the volume of noise generated by the jet efliux is substantially reduced.

What I claim as my invention and desire to secure by Letters Patent is:

1. Means for reducing the noise of the efflux of a turbo jet engine, comprising, in combination with an engine nacelle including an exterior shell enclosing a gas duct and open at its rear end to define a jet nozzzle for the efiiux of gases from the gas duct, a plurality of vanes each having a pointed vertex, and means for mounting said vanes in the etliux at a position close to and downstream of the jet nozzle with the vertex of each vane extending obliquely upstream toward the central axis of the jet nozzle to induce an admixture of additional air with the jet eliiux, said vane mounting means including carrier means slidably supported from the engine nacelle mounting each vane in equi-angular spaced relationship about the jet nozzle, and means for operating said vanes and carrier means for retracting and extending said vanes respectively from a position downstream of said jet nozzle to a position upstream of said jet nozzle, said operating means including a pair of fluid-pressure jacks each jack having a rain, the ram of one such jacks being connected to said carrier means, the ram of the other jack pivotally attached to its respective vane, the arrangement being such that the operation of the jacks is effective to extend and retract said vanes from their operative and inoperative position.

2. Means as claimed in claim 1 including a fixed housing on the outer wall of the engine nacelle for enclosing said operating means and carrier means when said vanes are in a retracted position.

3. Means as claimed in claim 2 including means to extend said vanes to their rear-most downstream position prior to the deflection of said vanes toward the central axis of the efilux of the jet nozzle.

4. Means as claimed in claim 2 including means for retracting said vanes from the efilux path prior to returning said vanes to their housed inoperative, position.

5. Means for reducing the noise of the efilux of a turbo-jet engine, comprising, in combination with an engine nacelle including an exterior shell enclosing a gas duct and open at its rear, end to define a jet nozzle for the etfiux of gases from the gas ductja plurality of. substantially triangular shaped vanes, and means for mounting said vanes in spaced non-abutting relationship downstream of said jet nozzle and exteriorly of said nacelle with a vertex of each vane extending obliquely upstream toward the central axis ofthe jet nozzle to induce an admixture of additional air With the jet efilux, each ofssaid vanesmounting means including a pair of fluid-pressure operated jacks each connected at one end to said nacelle and at their opposite ends to portions of References Cited in the file of this patent UNlTED STATES PATENTS 2,930,185 Tyler Mar. 29, 1960 3,032,981 Lawler May 8, 1962 3,059,426 Laucher et al Oct. 23, 1962 3,096,617 Bryant July 9, 1963 FOREIGN PATENTS 766,985 Great Britain Ian. 30, 1957 859,993 Great Britain Jan. 25, 1961 1,164,936 France May 19, 1958 O cation 1,054,848, printed April 9, 1959 (KL. 621) 37/02),

44 pp. spec, 2 shtQdWg. 

1. MEANS FOR REDUCING THE NOISE OF THE EFFLUX OF A TURBOJET ENGINE, COMPRISING, IN COMBINATION WITH AN ENGINE NACELLE INCLUDING AN EXTERIOR SHELL ENCLOSING A GAS DUCT AND OPEN AT ITS REAR END TO DEFINE A JET NOZZLE FOR THE EFFLUX OF GASES FROM THE GAS DUCT, A PLURALITY OF VANES EACH HAVING A POINTED VERTEX, AND MEANS FOR MOUNTING SAID VANES IN THE EFFLUX AT A POSITION CLOSE TO AND DOWNSTREAM OF THE JET NOZZLE WITH THE VERTEX OF EACH VANE EXTENDING OBLIQUELY UPSTREAM TOWARD THE CENTRAL AXIS OF THE JET NOZZLE TO INDUCE AN ADMIXTURE OF ADDITIONAL AIR WITH THE JET EFFLUX, SAID VANE MOUNTING MEANS INCLUDING CARRIER MEANS SLIDABLY SUPPORTED FROM THE ENGINE NACELLE MOUNTING EACH VANE IN EQUI-ANGULAR SPACED RELATIONSHIP ABOUT THE JET NOZZLE, AND MEANS FOR OPERATING SAID VANES AND CARRIER MEANS FOR RETRACTING AND EXTENDING SAID VANES RESPECTIVELY FROM A POSITION DOWNSTREAM OF SAID JET NOZZLE TO A POSITION UPSTREAM OF SAID JET NOZZLE, SAID OPERATING MEANS INCLUDING A PAIR OF FLUID-PRESSURE JACKS EACH JACK HAVING A RAM, THE RAM OF ONE SUCH JACKS BEING CONNECTED TO SAID CARRIER MEANS, THE RAM OF THE OTHER JACK PIVOTALLY ATTACHED TO ITS RESPECTIVE VANE, THE ARRANGEMENT BEING SUCH THAT THE OPERATION OF THE JACKS IS EFFECTIVE TO EXTEND AND RETRACT SAID VANES FROM THEIR OPERATIVE AND INOPERATIVE POSITION. 